Method for transporting a weft thread through a shed and loom for performing said method

ABSTRACT

A method for transporting a weft thread through a shed using one or more jet nozzles for a flowing transport fluid characterized in that the jet nozzle is fed by a cyclically varying quantity of transport fluid.

nited States Patent 51 June 27,1972

Vermeulen METHOD FOR TRANSPORTING A WEF T THREAD THROUGH A SHED AND LOOMFOR PERFORMING SAID METHOD Inventor: Geert Jan Vermeulen, Beethovenlaan34,

Deurne, Netherlands Filed: Oct. 22, 1970 Appl. No.: 83,175

Foreign Application Priority Data Net 22, 1969 Netherlands ..69l5973U..a'. CI 139/127 P, D03d/47/30 Field of Search ..139/122, 1, 127

[56] References Cited UNITED STATES PATENTS 3,229,725 1/1966 Saito..l39/127 P 2,936,002 5/1960 Opletal et al. 139/127 P PrimaryExaminer-Henry S. Jaudon AttorneyMarshall & Yeasting [57] ABSTRACT Amethod for transporting a weft thread through a shed using one or morejet nozzles for a flowing transport fluid characterized in that the jetnoule is fed by a cyclically varying quantity of transport fluid.

3 Claims, 2 Drawing Figures METHOD FOR TRANSPORTING A WEFI THREADTHROUGH A SHED AND LOOM FOR PERFORMING SAID METHOD BACKGROUND OF THEINVENTION The invention relates to a method for inserting a weft threadinto a shed making use of one or more jet nozzles for a flowingtransport fluid. The invention also relates to a loom of the type inwhich the wefts are transported through the shed by means of one or morejet nozzles for a flowing transport fluid.

Recent experiments with looms of the above mentioned type have shownthat a weft transported through the shed by a flowing fluid tends tolodge itself in the boundary layer surrounding the generally conical jetof the transport fluid.

It appeared furthermore that the energy transmission of a conical ordifferently shaped jet is greatest during the period immediately afterthe discharge of the jet begins in which said jet is still adjustingitself and therefore during a period in which the forming of theboundary layer is still in full swing. Where the nature of the jet conevaries less as a function of time, the energy transmission and thereforethe force acting on the thread becomes smaller.

SUMMARY OF THE INVENTION Making use of this principle the inventionproposes to feed the jet nozzle with a cyclically varying quantity oftransport fluid. The object aimed at thereby is to retard the buildingof the boundary layer and to obtain an optimal energy transmission fromthe transport jets to the wefts during the whole operative period of thejet nozzle while a weft is being transported through the shed.Experiments have shown that in this manner the necessary quantity oftransport fluid for transporting a weft in a predetermined time intervaland through a predetermined distance through a shed, which fluid may beair, can be decreased by -30 percent. The amount of the savings in fluidof course depends on the function according to which the transport fluidsupply to the jet noule varies.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view of ashed and one jet nozzle directed with its outflow opening into saidshed, and also the means to have the jet nozzle issue a pulsating jet oftransport fluid, and

FIG. 2 shows a diagram indicating the air consumption by applying such apulsating jet according to the invention as well as by applying aconstant jet.

In FIG. 1 the weft 2 presented at l is transported through the shedoutlined by the upper warp sheet 3, the lower warp sheet 4 and the reed5, by means of the jet cone 6 issued by the jet nozzle 7. The warp 2 iscontained in a boundary layer around the conical core of the jet 6. Thequantity of transport fluid, e.g., air issuing from the nozzle 7 perunit of time is not constant, however, but varies, e.g., according tothe curve 8 in FIG. 2. The curve 8 shows how the rate of flow of thetransport fluid through the jet nozzle varies as a function of time t,and indicates the quantity 0 of transport fluid which has to be suppliedper unit of time to the jet nozzle 7 in order to transport one weftthrough the shed within a predetermined time interval. The same figureshows the quantity of transport fluid which is necessary when keepingthe quantity of fluid issued per unit of time constant during the totaloperative period of the jet nozzle in order to transport one weft in thesame time through the same distance through a shed. It appears therebythat the total air consumption is substantially smaller when the jetnozzle issues a cyclically varying quantity of transport fluid than ifthe supply of transport fluid remains constant.

FIG. 1 furthermore shows schematically that for realizing a pulsatingtransport fluid jet a slide type valve 9 may be used, the slide 10 ofwhich is adapted to open and interupt in quick sequence thecommunication between the jet nozzle 7 and the source 11 of transportfluid by means of a schematically indicated actuating rod 12, which inits turn is controlled by a cam 13, the movement of which is derivedfrom the main shaft of the weaving loom. Also for this purposeadvantageously diaphragm valves may be used which comprise a valveclosure element with negligable inertia which is of great advantage.Pulsatingvalves of the electro-magnetic type may also be employed.

I claim:

I. A method of transporting a weft thread through a shed by discharginga jet of fluid under pressure to entrain the weft thread, wherein theimprovement comprises cyclically varying the amount of fluid dischargedin the jet during the transport of a weft thread through the shed.

2. A method according to claim 1 wherein a pulsating jet of fluid isdischarged during the transport of a weft thread through the shed, toentrain the thread.

3. A loom comprising a jet nozzle for discharging a jet of fluid totransport a weft thread through the shed, wherein the improvementcomprises apparatus for cyclically varying the amount of fluiddischarged in the jet during the transport of a weft thread through theshed.

* i I l

1. A method of transporting a weft thread through a shed by discharginga jet of fluid under pressure to entrain the weft thread, wherein theimprovement comprises cyclically varying the amount of fluid dischargedin the jet during the transport of a weft thread through the shed.
 2. Amethod according to claim 1 wherein a pulsating jet of fluid isdischarged during the transport of a weft thread through the shed, toentrain the thread.
 3. A loom comprising a jet nozzle for discharging ajet of fluid to transport a weft thread through the shed, wherein theimprovement comprises apparatus for cyclically varying the amount offluid discharged in the jet during the transport of a weft threadthrough the shed.